Laser diodes have been developed that produce substantial output powers that make possible a variety of applications. To further increase available optical power, laser diode assemblies have been produced in which output beams from a plurality of laser diodes are combined. In one example, laser diodes are arranged in a stair-step pattern and collimated beams from the laser diodes are formed into a beam stack. An objective lens receives the beam stack and focuses the beam stack to an input surface of an optical fiber. Total available power can be increased by increasing the number of laser diodes. However, the laser diodes used to form the beam stack must be spaced apart, so that a number of beams in a beam stack delivered to an objective lens is limited by a size of the beam stack. Thus, the number of beams that can be practically combined is limited. Conventional approaches to controlling beam stack size can be complex, and often require precision alignment in manufacturing. Alternative approaches are needed.